<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="utf-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"/>
    <title>分离式下拉菜单</title>
    <link href="css/bootstrap.css" rel="stylesheet">
    <style>
        body{
            padding: 10px;
        }
    </style>
</head>
<body>
<div class="container">
    <div class="btn-group">
        <button type="button" class="btn btn-danger">Action</button>
        <button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" >
            <span class="caret"></span>
        </button>
        <ul class="dropdown-menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li><a href="#">Separated link</a></li>
        </ul>
    </div>

</div>

<script src="js/jquery-1.12.4.js"></script>
<script src="js/bootstrap.js"></script>
</body>
</html>